﻿#region License

// PentaBiz - Sustainable Software Development Framework Copyright (C) 2013 Zoltán Csizmazia
// 
// This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version.
// 
// This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.
// 
// You should have received a copy of the GNU Lesser General Public License along with this library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 

#endregion

using System;
using System.Globalization;
using System.Linq.Expressions;
using System.Reflection;
using System.Windows.Controls;

namespace Csizmazia.WpfDynamicUI.WpfDynamicControl.ReflectiveWpfTools
{
    public class ReflectiveValidationMethodRule : ValidationRule
    {
        private readonly Func<string> _validationCallback;

        public ReflectiveValidationMethodRule(object viewModel, MethodInfo validationMethod)
        {
            if (viewModel == null) throw new ArgumentNullException("viewModel");
            if (validationMethod == null) throw new ArgumentNullException("validationMethod");

            //build expression for viewModel.ValidationMethod();
            _validationCallback = Expression.Lambda<Func<string>>(
                Expression.Call(Expression.Constant(viewModel), validationMethod)).Compile();
        }

        public override ValidationResult Validate(object value, CultureInfo cultureInfo)
        {
            string error = _validationCallback();

            var validationResult = new ValidationResult(string.IsNullOrEmpty(error), error);
            return validationResult;
        }
    }
}